<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script src="js/vue.js"></script>
</head>
<body>
<div id="biubiu">
    {{msg1}}
    <input type="text"  v-model="msg1"/>    <br>
    {{msg2}}{{msg3}}
    {{msg2+msg3}}
    <input type="text"  v-model.number.lazy="msg2"/>    <br>
    <input type="text"  v-model.number="msg3"/>    

</div>
<script>
    var vm=new Vue({
        el:"#biubiu",
        data:{
            msg1:"",
            msg2:0,
            msg3:0
        }
    })
    
</script>

</body>
</html>